1. Field of the Invention
One disclosed aspect of the embodiments relates to an imaging apparatus and an image forming apparatus employing a porous body for suppressing adhesion of foreign substances, such as dust.
2. Description of the Related Art
In imaging apparatuses, such as a digital camera etc, a photographing luminous flux is received by an imaging element, such as a CCD or a C-MOS, and then a photoelectric conversion signal output from the imaging element is converted to image data to be recorded in a recording medium, such as a memory card.
In such an imaging apparatus, a low pass filter or an infrared ray cut filter is disposed at the side of a subject of the imaging element. Particularly in a digital single-lens reflex camera in which the lens may be exchanged, a mechanical operation portion, such as a shutter, is disposed near an optical filter, such as a low pass filter, and foreign substances, such as dust generated from the operation portions, sometimes adhere to the low pass filter or the like. Moreover, dust or the like enters the camera main body from an aperture of a lens mount, and sometimes adhere to the low pass filter or the like during exchanging the lens. When dust adheres to the optical filter, such as a low pass filter, the adhesion point appears in a captured image as a black (gray) point, which sometimes reduces the quality of the captured image.
As a former technique for solving the problems, Japanese Patent Laid-Open No. 2002-204379 discloses a technique in which a dustproof film is provided at the side of a subject of an imaging element, and the dustproof film is vibrated by a piezoelectric element to remove dust. Moreover, Japanese Patent Laid-Open No. 2006-163275 discloses a technique in which the surface is coated in such a manner that dust or the like is hard to adhere.
In image forming apparatuses, such as an electrophotographic copying machine and an electrophotographic printer, a photoconductor is irradiated with laser light to form an electrostatic latent image. Then, the electrostatic latent image is developed with a toner, the toner image to be obtained is transferred onto a sheet-like recording medium, and thereafter the toner is heated and fixed with a fixing apparatus to thereby form an image on the recording medium.
Such an image forming apparatus has, in a housing, a light source which emits laser light based on image information, a rotary polygon mirror for deflecting and scanning the laser light emitted from the light source, an Fθ lens by which the laser light deflected and scanned by the rotary polygon mirror is imaged on a photoreceptor, a reflecting mirror, and the like. The image forming apparatus further has an optical apparatus which irradiates a photoconductor with laser light from an aperture in the housing. When there is dirt on a laser optical path, image omission arises at a portion corresponding to the dirt on the image, which sometimes reduces the image quality. Therefore, an apparatus has been proposed in which the entrance of dust, a toner, or the like is prevented by sealing the housing, and a transparent dustproof glass is attached to the aperture of the housing which emits laser light and a shutter is provided thereto, whereby dirt of the dustproof glass is prevented (Japanese Patent Laid-Open No. 11-167080).
Japanese Patent Laid-Open No. 2002-204379 mentioned above discloses a method for vibrating a dustproof film to thereby remove foreign substances, in which, in order to remove the foreign substance adhering to the dustproof film, high energy is required and also the structure becomes complicated.
The method in which the surface is coated in such a manner that dust or the like becomes difficult to adhere to the surface described in Japanese Patent Laid-Open No. 2006-163275 requires the formation of a plurality of optical films as an antireflection film for maintaining the optical performance.
According to the method in which the shutter is provided described in Japanese Patent Laid-Open No. 11-167080, the apparatus is easily damaged and also the structure becomes complicated.
Moreover, dust removal may not be satisfactorily achieved by the former techniques, and a further dust reduction has been required.